Rosin treatment



Patented Feb. 16, 1943 UNITED STATES PATENT OFFICE ROSIN TREATMENTLaszlo Auer, South Orange, N. ."I.

No Drawing. Application October 12, 1942- Serial No. 461,790

Z Claims.

GENERAL Fnrnn or INVENTION AND STATEMENT or Owners yro-abietic acid andd-pimaric acid amongst others. Such rosins commonly have an acid valueof from about 145 to 185, usually from about 160 to 168, and in theirnatural state they are ordinarily hard, brittle materials, of meltingpoint from about 70 C. to about 85 C.

Rosin is a valuable raw material for a number of commercial purposes,such as in paper sizing, soap manufacture, and especially in thecoatings and plastics industries. There are, in fact, a. number ofexamples in the art of use of various rosin derivatives for purposessuch as those mentioned. Some of the most important and common examplesoccur in the coatings industry, 1. e., use of rosin derivatives inpaints, varnishes and the like.

In its natural state, however, rosin is not well suited to manycommercial purposes for which it is potentially a valuable raw material.

The primary object of the present invention is to modify variousphysical properties of rosin, whereby to produce modified rosin productswhich are better adapted to many uses for which rosin or rosinderivatives are now employed. In addition, the modifications broughtabout in accordance with the present invention make it possible andadvantageous to use the modified rosin products for many purposes forwhich rosin in its natural state and also various derivatives thereofare not well suited.

To illustrate, reference is made to" coating compositions, such asvarnishes. In its natural state, rosin is a brittle material andtherefore yields a. brittle film when employed alone as varnish solids.Thus, rosin in its natural state does not'have film formingcharacteristics such that it may satisfactorily be employed alone asvehicle solids in a coating composition. According to'this-inventionmodifications are brought about in the rosin so as to secure a rosinproduct having drying or film forming characteristics which are wellsuited to the coating composition condition to a consistencyapproximating the and plastic compositions.

industry, thereby even making possible employment of the modified rosinproducts alone as vehicle solids in varnishes and the like. Usually,however, at least some drying or semi-drying oil is advantageously usedwith themodified products, particularly where flexibility of thecoatings is desired.

Because of the improved properties of the modified rosinproducts, suchproducts may be employed as a replacement ingredient, in substantialproportions, for linseed or other drying or semi-drying oils in paintsand other coating For certain special purposes in the soap and papersizing industries, the modified rosin products of this invention mayalso be of advantage, notwithstanding the fact that the modifiedproducts have a reduced acid value.

- One of the most important modifications brought about by the processof the invention is the softening or liquefying of the rosin, i. e., atleast some reduction of brittleness or in melting point, or both. Inaddition, the process of the invention is notable in its eifecton theacid value, the invention providing for appreciable reduction in acidvalue, as will further appear.

In referring to changes of this type and in making comparisons of themodified products with products not treated with modifying agents, it isto be understood that the statements regarding changes and comparisonsare always made on the basis of a relation between the product treatedwith a modifying agent and a product treated in exactly the same manner(heating, etc.) but without a modifying agent. The latter is oftenherein referred to as a blank or "control experiment.

According to the invention, by appropriate control of treatmentconditions, and by appropriate selection of materials, the degree ofsoftening or liquefaction and also of acid value may be regulated tomeet various different requirements.

For instance, according to the invention, it is possible to veryextensively soften the rosin, or to very extensively lower the acidvalue, or both.

Although the invention is not limited thereto, it is of especialimportance and advantage in accordance with the invention" to subjectthe rosin to treatment for a time and under conditions such as to changethe physical character of the rosin from its natural hard andbrittleso-called cold flow, 1. e., a consistency according to which thematerial will gradually flow at normal room temperatures, so that if ablob of the modified rosin is placed on a flat surface, it will more orless gradually flatten out, often at a rate which is not observable withthe eye. For many purposes a liquefaction at least to this degree isdesirable.

For certain purposes it is advantageous that the rosin be liquefied evento the extent of becoming a mobile liquid, similar, for instance, to theconsistency of certain oils, such as bodied linseed oil.

My preferred range of liquefaction extends from about the consistency ofa viscous oil to about the cold flow consistency above mentioned,although it is to be understood that a greater or a-lesser degree ofliquefaction is also contemplated.

THE MODIFICATION Paocsss The process of the invention involves heatingthe rosin in the presence of a modifying agent of the type mentionedhereinafter, the duration of heating, temperature and other treatmentconditions, as more fully explained herebelow, being controlled inaccordance with the extent and type of modification desired.

In general, modifying agents employed in accordance with this invention,and also in accordance with certain of my copending applications,identified hereinafter, are polar compounds. The present application isparticularly directed to the use of certain metal salts as modifyingagents.

A particularly advantageous group of metal salts are metal salts ofcertain metals which form amphoteric compounds, such for instance, aschromium, which forms chromates and dichromates. In these salts, thechromium or similar metal forms an acid radical.

Various metals may be used as cations to form the salts herein claimed,one suitable class being the alkali metals, the alkaline earth metals,magnesium and zinc. Ammonium is considered herein as belonging'to thealkali metals, since it behaves similarly.

In addition to the above, certain heavy metals, such as lead mayappropriately be combined with chromium-containing anions to constitutea metal salt also effective for the purposes herein contemplated.

By selection of the modifying agent employed, and by appropriatevariations in treatment procedure, temperature, time, etc., I am enabledto produce modified rosin products having quite a wide range ofproperties. In fact, according to the invention, it is possible tosecure a modified product in which either the acid value or the meltingpoint is lowered or in which both of these properties are simultaneouslylowered to an appreciable degree. Although the modifying agentsdisclosed and claimed herein bring about some degree of softening orliquefaction of the rosin, the degree of softening is not as great asmay be secured with certain other modifying agents disclosed incopending applications mentioned hereinafter. Products of .quite a.widerange of acid value are obtainable, however, by the use of the modifyingagents herein claimed; In carrying out the process, the rosin is heatedbetween about 250 C. and about 350 C., depending upon the agent selectedand the degree and type of modification desired. Some agents should beheated above about 270 C. in order to secure appreciable modification ofthe properties of the rosin. I

Anywhere from a trace, for or .5% up to about 30% of the metal salt mayinstance, .o 1%' be employed, although I have found a particularlyadvantageous range to be from about av to about 10%.

Thorough dispersion of the modifying agent in the rosin is of importanceand appropriate control of temperature and time both contribute tobringing about such thorough dispersion. Agitation may also be employedas an aid to secure thorough dispersion of the modifying agent. Usuallynot more than a few hours treatment on temperaturev will be foundsufilcient, for in- 1 stance, from about one hour to about five hours,

although in some cases, the reaction proceeds very rapidly, requirin notmore than about one half hour.

Another important consideration is that the reaction is preferablycarried out in the absence of air, or out of contact with anysubstantial quantity of air. For this'purpose the reaction may becarried out in a closed vessel, though not usually under a positivepressure, so that the gases or fumes of the reaction released from themodifying agent serve to exclude the air.

Vacuum is also effective for the purpose of excluding air and, inaddition, reduction in contact of air may be brought about by blanketingthe surface of the reaction mixture with some inert gas, such as S02,CO2, or nitrogen. Where vacuum is used, a pressure, for instance, ofabout mms. Hg toabout 450 mms. Hg will be found effective, althoughhigher or lower pressure may also be used. Whatever means or procedureis employed, it is of advantage to so conduct the process as to reduceoxygen concentration in the reaction vessel and prevent entrance offresh air or oxygen to the reaction mixture.

Some more or less general considerations regarding the process should benoted, as follows:

Although the complete mechanism of modification may not be fullyunderstood, it may be mentioned that rosin is an organic isocolloid. i.e., a colloidal system in which the dispersed phase and the dispersionmedium are both of the same chemical composition, though present indifferent physical states.

By modification I believe that the relationship or relative proportionsof the dispersed phase and dispersion medium may be altered. Moreover,the modification process apparently also involves decarboxylation, theextent of which is usually incomplete. Still further. formation of asoap may occur, by reaction of the rosin with the metal of the compoundemployed as modifying agent. tion may be responsible, in some instances,for at least a part of the reduction in acid value: and in some cases.may further have the effect of holding the melting point relativelyhigh.

In fact, some of the foregoing effects or reactions (particularly withrespect to the physical consistency of the modified product) may work inone direction and others'ln the opposite direction. Thus, when soaps areheated with rosin under certain reaction conditions they may increasethe melting point of the rosin, Therefore a partial soap formationduring the process may, so to speak, counteract the liquefactionprocedure and the end melting point may be the differential resultof theliquefying action of the modifying agent and of the solidifying actionof a soap formation.

Possibly also non-volatile aggregates or polymers are formed.

In considering the nature of the modifications, it is to be noted that,while some small loss in This soap formsweight may occur byvolatilization (usually not more than about 15-20%), no appreciablefractional or destructive distillation takes place. With appropriateprecautions to avoid distillation the process can usually be carried outwithout loss of more than or such small loss as does occur usuallycomprising water, CO2, etc., at least in major part. As a precaution,the temperature should be kept below the boiling or distillation pointof the main reaction product, under the applied reaction conditions oithe process. By this precaution, destructive distillation or cracking ispositively avoided.

The modified rosin product is quite unique,

since the rosin molecule retains almost as manycarbon atoms as arepresent in the initial basic constituents of the rosin, the number-oicarbon atoms being reduced only by that number involved in thedecarboxylation. Still further, the types of constituents of themodified rosin are very few in number, probably not more than two I orthree, and these constituents are characterized by boiling points alllying within a. narrow and relatively high temperature range, as can bedemonstrated by subsequent distillation of the modified products. Themodified products, for practical purposes, are non-volatile when exposedto the air.

It is of importance in securing various of the foregoing characteristicsthat the reaction take place without any appreciable concurrentdistillation. In addition, the absence oi air and/orcontrol oftemperature are important in avoiding destructive distillation.

Whatever the exact nature of the chemical. colloidal and/or physicalchanges which are brought about, in general the treatment provided inaccordance with the present invention reduces the acid value of themodified product and also softens or licuefies the material. Thesechanges, together with others which usually take place, such asimparting drying characteristics to the rosin, and improving filmforming properties oi the modified products as compared with untreatedrosin in the absence of other vehicle solids, for instance, makepossible or practicable use of my modified rosin products for manypurposes for which rosin in its natural state is not suited, or at leastnot well adaptable, and for which many known rosin derivatives arelikewise not satisfactory.

By appropriate selection of modifying agent and treatment conditions,such as temperature, time, vacuum, etc., I am enabled to control variousphysical properties of the modified products, and notably the acidvalue, saponification value and physical consistency. In general, themost valuable.- modified products have, for instance, a saponificationvalue not exceeding 120.

Exmuzs A series oi comparative experiments were conducted under closelycontrolled conditions, was to secure accurate comparative results,demonstrating the relative effectiveness of' a number of diflerent saltsin the modification of rosin.

In all examples of this series, W Wood rosin (Newport Industries) wasemployed. In all examples a batch of 1,000 gms. of rosin was treatedwith 50 gms. of the salt, the rosin and modifying agent being heatedtogether in a three liter distilling flask under a pressure of 400 mms.Hg. Different temperatures were used in diflerent examples, as isindicated in the table given herebelow.

- Plastic=consistency such that the material may For the sake of furthercomparison and analysis, a similar batch of 1,000 gms. of WW wood rosinwas heated as a blank experiment (see B in the table below), under theconditions above specified but without the presence of a modifyingagent, this blank" experiment being conducted at a temperature of 290C., which temperature was also used in-a number of the other Moreover,'asimilar b1ank" experithe table below) The initial untreated rosin had anacid value of about 169 and a melting point of about 81, as is shown inthe table-see item A".

All temperatures are given in degrees centigrade.

Table of comparative experiments Ex. Acid Iodine Melting Consist- No.Agent Temp value value point ency 1 Lead chro- 290 101.7 145.5 60Slightl mate. plast c 2 Lead chro- 320330 68.1 111.6 Plastic.

mate. 3 Potassium 290 65.5 1562 73 Solid.

: dichromatc. 4 do 320-330 25.5 1%;5 53 Slightly plutic A (WW wood 169No.2 81 Brittle rosin withsolid. out any treatment). B (Heated 200 130.3150.8 68 Do.

w i t h o u t agent). 0 do 320-330 97.8' 129.1 Plastic.

The designations under the "Consistency column may be further explainedand amplified as follows:

Solid=consistency harder than that on which an ,impression can be madewith the finger nail. Slightly plastic= consistency such that animpression can be made with the finger nail.

sometimes also displaying some degree of cold vwith ease be deformedwith the fingerand manifesting free cold flow characteristics.

The treatment temperature-indicated in the foregoing table. represents afairly close average maintained throughout the five hour treatmentperiod (usually within 10 C. plus or minus).

From the examples given above it will be noted that appreciable changein acid value is brought about in comparison with the Blank" experiments as a result of treatment in accordance with e the presentinvention.

In addition, the Physical consistency of the nets of Examples 1 and 2both were softer or had lower melting points than the corresponding"blank experiments. Although the melting points of Examples 3 and 4 weresomewhat higher -than the corresponding "blank experiments, it

may be noted that the products were of difierent consistency, and didnot display the brittleness of the untreated rosin. In any event, themodification, including decarboxylation proceeded to a considerableextent, as is demonstrated by the relatively low acid values of theproducts of Examples 3 and 4. The lowering of the acid value may becaused in part by soap formation, such soap formation possibly alsobeing responsible for the higher melting point.

Although the color of the product is sometimes changed appreciably bythe process, it may be noted that products of quite light color may alsobe secured, this being of advantage for a number of purposes, forinstance,-in the varnish industry.

Certain variations in procedure may be adopted.

For example, instead of using vacuum during the treatment period, otherprocedure may be adopted with a view to excluding air from the reaction.The form of the reaction vessel employed may be such that gases evolvedfrom the reaction will serve to effectively exclude air, withoutapplying vacuum. Furthermore, certain gases, such as $02, CO: ornitrogen can be either bubbled through the reaction mass or employed asa blanket on the surface of the batch undergoing treatment. Expedientsof this type not only serve to exclude the air from the reaction but mayalso be utilized for their supplemental eil'ect on the material beingtreated, this subject being more fully considered in my copendi'ngapplication Serial No. 386,371, filed April 1, 1941, of which thepresent application is a continuation. It is here further noted thatcertain features herein disclosed are also disclosed in my prior U. S.applications Serial No. 318,650, filed February 12, 1940, Serial No.359,425 (now Patent No. 2,213,944) and Serial No. 143,786 (now PatentNo. 2,189,772)

Moreover, as disclosed in the above mentioned copending applications,stillother variationsin process may be employed for a number ofdifferent purposes, but it is not thought necessary to discuss thesefully herein, since reference may be made to the copending applicationsfor that purpose. In passing, however, it is noted that additionaltreating agents, of a supplemental character, may also be present duringthe reaction, among which might be mentioned dissolution promotingagents of the type disclosed in my issued Patent No. 2,293,038. Variouscombinations of modifying agents may also be used for differentpurposes, including combinations of the modifying agents abovedisclosed, as well as combinations of the modifying agents hereindisclosed with agents disclosed in other of my applications mentionedabove as well as hereinafter.

It is further to be noted that in general increasing any one or all ofthe variables: namely, temperature, time of treatment and percentage ofmodifying agent, increases the extent of modification. It will beunderstood that the foregoing is a general rule normally applicablewithin the ranges of operation above'indicated, although, as to at leastsome variables, there may be limits beyond which the general rule doesnot apply. For instance, excessive increase in temperature maysubstantially alter the character of the process. On the other hand, ininstances where a soap forming metal is present in the modifying agent,excessive increase in percentage of modifying agent may not yield assoft a product as a lower percentage of the modifying agent.

In considering the starting material onwhich the process may beemployed, it is first noted that the process brings about changes bothof a colloidal and also of a chemical nature. It is important, however,to bear in mind that the process essentially involves a reaction withthe rosin molecule, that is, with the type of molecules of which thebasic constitutents of natural rosin are com posed. Therefore, whilerosin itself. such as'gum or wood resins, represents perhaps the mostimportant starting material to which the process is reaction will takeplace wherever the rosin molphysical or chemical state or environment"of the rosin molecule is not such as to prevent the reaction from takingplace.

'It may also be mentioned that there are other natural resins, such ascopals, which act similarly to rosin by treatment in accordance withthis invention. In fact, the reaction may be carried out on any of thenatural resins containing high molecular resin acids. Therefore,wherever any such other natural resin behaves similarly to rosin, it isherein considered as an equivalent.

Copals are fossil gums which have to be fused" before becoming solublein organic solvents and miscible with fatty oil. When copals are used inthe present process, they should be employed in the fused state.

The modified product of this invention may if desired, be subject toother treatment, depending upon the use for which it is intended. Thus,for example, the modified products may be vulcanized with sulphur. Themodified resin products secured in accordance with the foregoing, may bevulcanized as such, or in solutions, such as varnish fiiutions, (in thelatter case with sulphur chlo- Further, they may be converted intoemulsions and used for various purposes in that form.

In the event sulphur or other sulphur-like vulcanizing agents are used,vulcanization, for certain purposes, is desirably carried out attemperatures between about C. and 200 C. For other. purposes wherevulcanization is to be effected at lower temperatures, for instance, atroom temperature, sulphur chloride, or similarly acting vulcanizingagents, should be used. In instances where the vulcanization is carriedout in a varnish solution, the sulphur chloride treatment is especiallypractical.

As .is mentioned in my copending application Serial No. 386,371, filedApril 1, 1941, the modified rosin products may be subject to still othersupplemental treatments, such for instance,-as esteriflcation, as bytreating with glycerin or other polyhydric alcohols, such as glycols,pentaerythritol, mannitol, sorbitol, etc.

The vulcanized liquefied resin products made in accordance with theinvention have valuable properties for a number of purposes includingthe making of protective'coatings, some of these vulcanized productsbeing useful as plasticizers for coating compositions and plastics.

It is noted that in copending applications filed concurrently herewith,certain other modifying agents are claimed in the treatment of rosin:See applications Serial Nos. 461,787; 461,791 to 461,797 inclusive; and461,800. Other rosin treatment is also disclosed in copendingapplication 447,439 filed June 17, 1942.

I claim:

1. A process for making a modified rosin prod uct from hard and brittlerosin, which process comprises incorporation in the rosin of from 2% to10% of a metal salt containing chromium in the anion and heating themixture out of contact with the atmosphere between about O. and

35090., but not above the temperature at which appreciable destructivedistillation occurs under the conditions of the treatment, the time oftreatment being suflicient to reduce the acid value of the rosin ascompared with the acid value of the same rosin heated to the sametemperature under the same treatment conditions but without a mod-.-

ifying agent.

2. A process in accordance with claim 1 in which the heating iscontinued at least until the resultant mixture, when cooled, has coldflow consistency.

which the reaction mixture is heated at least to 7. A process inaccordance with claim 1 in which the heating is eflected under vacuum.

LAszLO AUER.

